package java.security.cert;

import java.io.PrintStream;
import java.io.PrintWriter;
import java.security.GeneralSecurityException;

/**
 * An exception indicating one of a variety of problems encountered
 * when building a certification path with a
 * <code>CertPathBuilder</code>.<br />
 * <br />
 * A <code>CertPathBuilderException</code> provides support for
 * wrapping exceptions. The {@link #getCause() getCause} method
 * returns the throwable, if any, that caused this exception to be
 * thrown.<br />
 * <br />
 * <strong>Concurrent Access</strong><br />
 * <br />
 * Unless otherwise specified, the methods defined in this class are
 * not thread-safe. Multiple threads that need to access a single
 * object concurrently should synchronize amongst themselves and
 * provide the necessary locking. Multiple threads each manipulating
 * separate objects need not synchronize.
 *
 * @see CertPathBuilder
 **/
public class CertPathBuilderException extends GeneralSecurityException
{
    private Throwable cause;

	/**
	 * Creates a <code>CertPathBuilderException</code> with
	 * <code>null</code> as its detail message.
	 **/
    public CertPathBuilderException() {}

	/**
	 * Creates a <code>CertPathBuilderException</code> with the
	 * given detail message. The detail message is a
	 * <code>String</code> that describes this particular
	 * exception in more detail.
	 *
	 * @param msg the detail message
	 **/
    public CertPathBuilderException(String message)
    {
	super(message);
    }

	/**
	 * Creates a <code>CertPathBuilderException</code> that wraps
	 * the specified throwable. This allows any exception to be
	 * converted into a <code>CertPathBuilderException</code>,
	 * while retaining information about the wrapped exception,
	 * which may be useful for debugging. The detail message is
	 * set to <code>(cause==null ? null : cause.toString())</code>
	 * (which typically contains the class and detail message of
	 * cause).
	 *
	 * @param cause the cause (which is saved for later
	 * retrieval by the {@link #getCause()} method). (A null value is
	 * permitted, and indicates that the cause is nonexistent or
	 * unknown.)
	 **/
    public CertPathBuilderException(String message, Throwable cause)
    {
	super(message);
	this.cause = cause;
    }

	/**
	 * Creates a <code>CertPathBuilderException</code> with the
	 * specified detail message and cause.
	 *
	 * @param msg the detail message
	 * @param cause the cause (which is saved for later retrieval
	 * by the {@link #getCause()} method). (A null value is
	 * permitted, and indicates that the cause is nonexistent or
	 * unknown.)
	 **/
    public CertPathBuilderException(Throwable cause)
    {
	this.cause = cause;
    }

	/**
	 * Returns the internal (wrapped) cause, or null  if the cause
	 * is nonexistent or unknown.
	 *
	 * @return the cause of this throwable or <code>null</code> if
	 * the cause is nonexistent or unknown.
	 **/
    public Throwable getCause()
    {
	return cause;
    }

	/**
	 * Returns the detail message for this CertPathBuilderException.
	 *
	 * @return the detail message, or <code>null</code> if neither
	 * the message nor internal cause were specified
	 **/
    public String getMessage()
    {
	String message = super.getMessage();

	if ( message == null && cause == null )
	    return null;

	StringBuffer s = new StringBuffer();
	if ( message != null )
	{
	    s.append( message + "\n" );
	}
	if ( cause != null )
	{
	    s.append( "Cause:\n" + cause.getMessage() );
	}
	return s.toString();
    }

	/**
	 * Returns a string describing this exception, including a
	 * description of the internal (wrapped) cause if there is
	 * one.
	 *
	 * @return a string representation of this
	 * <code>CertPathBuilderException</code>
	 **/
    public String toString()
    {
	String message = getMessage();
	if ( message == null )
	    return "";

	return message;
    }

	/**
	 * Prints a stack trace to <code>System.err</code>, including
	 * the backtrace of the cause, if any.
	 **/
    public void printStackTrace()
    {
	printStackTrace( System.err );
    }

	/**
	 * Prints a stack trace to a <code>PrintStream</code>,
	 * including the backtrace of the cause, if any.
	 *
	 * @param ps the <code>PrintStream</code> to use for output
	 **/
    public void printStackTrace(PrintStream ps)
    {
	super.printStackTrace(ps);
	if ( getCause() != null ) {
	    getCause().printStackTrace(ps);
	}
    }

	/**
	 * Prints a stack trace to a <code>PrintWriter</code>,
	 * including the backtrace of the cause, if any.
	 *
	 * @param ps the <code>PrintWriter</code> to use for output
	 **/
    public void printStackTrace(PrintWriter pw)
    {
	super.printStackTrace( pw );
	if ( getCause() != null ) {
	    getCause().printStackTrace( pw );
	}
    }
}

